1. Field of the Invention
The present disclosure relates to a display device, and more particularly, to an organic light emitting diode (OLED) display device and a driving method thereof.
2. Discussion of the Related Art
With the advancement of information-oriented society, various requirements for display field are increasing, and thus, research is being done on various flat panel display devices that are thin and light, and have low power consumption. For example, the flat panel display devices are categorized into liquid crystal display (LCD) devices, plasma display panel (PDP) devices, OLED display devices, etc.
Especially, OLED display devices that are being actively studied recently apply data voltage (Vdata) having various levels to respective pixels to display different grayscale levels, thereby realizing an image.
To drive the pixels, various control signals for controlling a plurality of transistors such as switching transistors, driving transistors, and emission control transistors are necessary. The plurality of control signals, for example, include a scan signal (Scan), a control signal (Control), and an emission control signal (Em).
Particularly, an emission control transistor that is driven by the emission control signal needs to hold a turn-on state for a relatively long time, and thus, the emission control transistor is quickly deteriorated, causing the degradation of image quality.
Moreover, when the threshold voltage of a driving transistor is a negative voltage, it is unable to compensate for the negative threshold voltage, and thus, the level of a current flowing in an OLED is largely changed according to the deviation of the negative threshold voltage and the deviation of a low-level power supply voltage due to IR drop, causing the degradation of image quality.